High efficient light-emitting diodes with improved the balance of electron and hole transfer via optimizing quantum dot structure

Abstract

Modifying the structure of quantum dots (QDs) is regarded as one of the promising way to improve the charge transfer balance of quantum dot light-emitting diodes (QLEDs). In this paper, we report highly bright Cd0.1Zn0.9S/CdSe/CdS quantum dots by optimizing the CdSe shell and CdS outer shell and explore their application in QLEDs. We find that with appropriate thicknesses of CdSe and CdS shell the charge transfer balance of the device can be improved. Comparable studies on two red QLEDs with Cd0.1Zn0.9S/CdSe/CdS and CdSe/CdS show that the external quantum efficiency (EQE) of the Cd0.1Zn0.9S/CdSe/CdS device is over 3 folds higher than its counterpart, implying that structure of the QDs plays an important role in controlling the charge transfer balance of the QLEDs.